Inverter-Integrated Electric Compressor

ABSTRACT

Provided is an inverter-integrated electric compressor excellent in joining strength and joining reliability at electrical joint. An inverter-integrated electric compressor wherein a motor is incorporated and a motor drive circuit including the inverter is surrounded by a compressor housing, characterized in that a bus bar joint section at which bus bars are electrically joined together is provided in the motor drive circuit, and a tip of at least one of the bus bars, the tip being located at the bus bar joint section, is split into small joining sections.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an inverter-integrated electric compressor in which a motor drive circuit including an inverter is mounted in a compressor, and specifically relates to an inverter-integrated electric compressor which is designed to improve the working efficiency for mounting an electronic component such as IPM, which is weak to thermal stress, in the motor drive circuit.

BACKGROUND ART OF THE INVENTION

As disclosed in Patent document 1, known is a structure of an inverter-integrated electric compressor in which a motor drive circuit including an inverter is mounted in a compressor, where the motor drive circuit is coated with insulative resin coating material, and where the motor drive circuit, lead wires and connection terminals are provided in a closed space surrounded by a metal wall. In the motor drive circuit of the compressor, used are electronic components, such as IPM (Intelligent Power Module) having an inverter function and being weak to heat.

In addition, known is a joint structure body which consists of joined members configuring an electric circuit, wherein a joint has a plurality of joining spots, as shown in Patent document 2. Such a joining structure body is provided with a plurality of joining spots at a joint section, so that the joint section is ensured to have sufficient strength.

PRIOR ART DOCUMENTS Patent documents

-   Patent document 1: JP2008-202564-A -   Patent document 2: JP2004-185953-A

SUMMARY OF THE INVENTION Problems to be solved by the Invention

In the inverter-integrated electric compressor which is disclosed in Patent document 1, terminals such as a bus bar can be used at an electrical joint. In such a case, the terminals can be connected to each other with bolts or screws, and alternatively can be connected to each other by welding. However in a case where components have to be mounted in a predetermined space, the welding may be the only method applicable.

However, because an inverter-integrated electric compressor requires electric current greater than general compressors, when the contact resistance at the joint section is comparatively high, heat generation from the joint section might adversely affect various devices. In addition, when a compressor is mounted to an automotive engine as being used in an air conditioning system for vehicles, the joint section is required to have joining strength and joining reliability enough to endure a severe condition of high temperature in an engine room.

Therefore, being focused on the above described problems, an object of the present invention is to provide an inverter-integrated electric compressor, which is excellent in joining strength and joining reliability at the electrical joint.

Means for Solving the Problems

To achieve the above described object, an inverter-integrated electric compressor according to the present invention is an inverter-integrated electric compressor, wherein a motor is incorporated and a motor drive circuit including an inverter is provided in a housing space surrounded by a compressor housing, characterized in that a bus bar joint section at which bus bars are joined together to connect electrically is provided in the motor drive circuit, and a tip, which is located at the bus bar joint section, of at least one of the bus bars is split into small joining sections.

Because the tip, which is located at the bus bar joint section connecting the bus bars electrically, of at least one of the bus bars is split into small joining sections in the inverter-integrated electric compressor according to the present invention, each other's bus bar can be joined at a plurality of spots, so that the connection strength and the connection reliability can be ensured. In addition, because they can contact with a large contact area, contact resistance at the joint section can be reduced. Further, in employing a joint method such as welding which requires to be heated, thermal stress to electronic components can be reduced in the present invention more than in a conventional method where the total area of welded spots are concentrated to one spot. In the present invention, welding is performed as dispersed to a plurality of welded spots, so that energy (Voltage×Current×Weld time, for example) applied in the weld time can be suppressed. Furthermore, because welded spots are dispersed and therefore each welded area is segmentalized, a welding machine and a clamping jig which are used in welding can be downsized, so that the productivity of compressors is improved.

In the present invention, it is possible that the tips of both bus bars are provided with small joining sections. Because the tips of both bus bars are provided with similar small joining sections, relative positioning between bus bars can be easily performed. In a case where the bus bar of the inverter-integrated electric compressor of the present invention is welded by a TIG welding, if the tips of both bus bars are provided with small joining sections, the arc for the TIG welding can be accurately jetted toward the spot to be welded, so that the connection reliability at the welded spot is ensured.

Because the motor drive circuit board is often provided with a lot of electronic components which are weak to thermal stress, the present invention makes it possible to effectively achieve reducing thermal load in a case where at least one of the bus bars is connected to a board of the motor drive circuit. As well, because IPM is weak to thermal stress, the present invention makes it possible to effectively achieve reducing thermal load in a case where at least one of bus bars is provided on an IPM. Furthermore, it is preferable that at least one of the bus bars is provided as standing up from the board of the motor drive circuit. Thus the bus bar is provided as standing up from the board, so as to make it easy to perform relative positioning with the bus bar provided in a member, such as a case member, which houses the motor drive circuit.

The inverter-integrated electric compressor according to the present invention is applicable to all types of compressors substantially, and specifically, is suitably used as a compressor for automotive air conditioning systems which are often installed in a narrow space and are sensitive to thermal stress. In addition, when the compressor is mounted to an automotive engine, the joint section can be given joining strength and joining reliability enough to endure a severe condition of high temperature in an engine room.

Effect according to the Invention

In the inverter-integrated electric compressor according to the present invention, the tip of at least one of the bus bars is split into small joining sections at the bus bar joint section, so that the connection strength and the connection reliability can be improved. Further, because the joint section can contact with a large contact area, contact resistance is reduced so as to suppress heat generation even when great electric current flows into the joint section under operation of the compressor. Furthermore, because the tips of both bus bars are segmentalized into small joining sections, relative positioning between the bus bars can be easily performed and the productivity of the compressor can be improved.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a schematic longitudinal sectional view, showing a basic configuration of an inverter-integrated electric compressor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram which shows like an electric circuit an air conditioning control mechanism including the compressor in FIG. 1.

FIG. 3 is a perspective view showing a connection state between a case member, which houses motor drive circuit 21 shown in FIG. 1, and IPM 25 shown in FIG. 1.

FIG. 4 is a partial enlarged perspective view, showing enlarged joint sections of bus bars 60, 70 shown in FIG. 3.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

Hereinafter, desirable embodiments will be explained as referring to figures.

FIG. 1 shows a scroll-type electric compressor for automotive air conditioning systems, as a basic configuration of inverter-integrated electric compressor 1 according to an embodiment of the present invention. In FIG. 1, symbol 2 implies a compression mechanism consisting of fixed scroll 3 and movable scroll 4. Movable scroll 4 is swung relative to fixed scroll 3 while its rotation is prevented with ball coupling 5. Motor 7 is incorporated in compressor housing (center housing) 6, and main shaft 8 (rotation shaft) is driven to rotate by built-in motor 7. The rotational movement of main shaft 8 is converted into the orbital swinging movement of movable scroll 4, through eccentric pin 9 and eccentric bush 10 which is rotatably engaged therewith. In this embodiment, compressor housing (front housing) 12 is provided with suction port 11 for sucking refrigerant as fluid to be compressed. Sucked refrigerant is led to compression mechanism 2 through a placement part of motor 7. The refrigerant which has been compressed with compression mechanism 2 is delivered to an external circuit, through discharge hole 13, discharge chamber 14 and discharge port 16 which is provided in compressor housing (rear housing) 15.

Motor drive circuit 21 for motor 7 is provided in compressor housing 12 (front housing). In more detail, motor drive circuit 21 is provided at the external side of partition wall 22 which is formed in compressor housing 12 against the side of refrigerant suction passageway. Motor drive circuit 21 supplies electricity through seal terminal 23 (an output terminal of motor drive circuit 21), which is attached thereto by penetrating partition wall 22, and lead wire 24 to motor 7, while the refrigerant suction passageway side and the side of motor drive circuit 21 are sealed in the placement part of motor 7. Because motor drive circuit 21 is provided at the external side of partition wall 22, at least one part of electric components including motor drive circuit 21 can be cooled with sucked refrigerant by heat exchange.

Motor drive circuit 21 includes IPM (Intelligent Power Module) 25 having inverter function and control circuit 26, and electric components such as capacitor 27 are provided either integrally with it or separately from it. Motor drive circuit 21 is connected to an external power supply (not shown) through connector 28 as an input terminal. The aperture side to the outside of compressor housing 12, which mounts these electric components including motor drive circuit 21, is covered as sealed with lid member 29, and these electric components are protected by lid member 29.

The above-described configuration can be shown like an electric circuit, as in FIG. 2. As shown in FIG. 2, electric compressor 1 is provided with motor drive circuit 21. Output electric power is supplied from motor drive circuit 21, through seal terminal 23 and lead wire 24, to each motor wire wrap 41 of built-in motor 7, so that motor 7 is driven to rotate and compression is performed by compression mechanism 2. Motor drive circuit 21 has high voltage circuit 30 for motor drive and low voltage circuit 45 for control with motor control circuit 44 to control each power element 43 (switching element) of inverter 42 in high voltage circuit 30 for motor drive and low voltage circuit 45 for control is comprised in control circuit 26. The electric power is supplied from external power supply 46 (e.g. battery) through connector 47 for high voltage into high voltage circuit 30 for motor drive, and then supplied through noise filter 37 and capacitor 27 for smoothing to inverter 42. Direct current, which is input from external power supply 46, is converted into pseudo-triphase current by inverter 42, and then supplied to motor 7. For example, low voltage electric power is supplied to motor control circuit 44 through connector 49 for control signal from air conditioning control device 48 of a vehicle. In FIG. 2, connector 49 for control signal and connector 47 for high voltage are illustrated at positions apart from each other, but actually, are mounted in the same connector 28 shown in FIG. 1. Shield plate 31, which is fixed to control circuit 26, is interposed between high voltage circuit 30 for motor drive and control circuit 26 with low voltage circuit 45 for control, and it covers over high voltage circuit 30 for motor drive as much as possible so as to block the effect of noise on the side of low voltage circuit 45 for control from high voltage circuit 30 for motor drive.

FIG. 3 is a perspective view, showing a state where electronic components, such as IPM 25, are connected to case member 58 which houses motor drive circuit 21 of the compressor shown in FIG. 1. Bus bar 60 as an electrical connection terminal provided on an end face of case member 58 is connected electrically by TIG welding to bus bar 70 provided in IPM 25. In addition, a part of case member 58 is perforated along bus bar 80, so as to form component affixing hole 59. A coil component (not shown) for noise removal of motor drive circuit 21 is inserted into component affixing hole 59, and is electrically connected to bus bar 90, which is provided in the coil component, by TIG welding. Bus bars 80, 90 are welded on small joining sections 81, 91 each having three split tips. Besides, capacitor 27 and a board of motor drive circuit 21 can be exemplified as various electronic components to be inserted in component affixing hole 59.

FIG. 4 is a partial enlarged perspective view, showing enlarged joint sections of bus bars 60, 70 shown in FIG. 3. In order to facilitate visualization, case member 58 and IPM 25 in FIG. 3 have not been illustrated. Bus bars 60, 70 are welded on small joining sections 61, 71, which are formed by dividing tips of bus bar 60 and bus bar 70. Because the tips of bus bar are divided into small joining sections, the arc for the TIG welding can be accurately jetted toward the spot to be welded, and both high connection strength and connection as well as low contact resistance can be performed.

INDUSTRIAL APPLICATIONS OF THE INVENTION

The inverter-integrated electric compressor according to the present invention is applicable to all types of compressors substantially, and specifically suitably used as a compressor for an automotive air conditioning system which is mounted in a narrow space and is sensitive to thermal stress.

EXPLANATION OF SYMBOLS

-   1: inverter-integrated electric compressor -   2: compression mechanism -   3: fixed scroll -   4: movable scroll -   5: ball coupling -   6: compressor housing (center housing) -   7: motor -   8: main shaft -   9: eccentric pin -   10: eccentric bush -   11: suction port -   12: compressor housing (front housing) -   13: discharge hole -   14: discharges chamber -   15: compressor housing (rear housing) -   16: discharge port -   21: motor drive circuit -   22: partition wall -   23: seal terminal -   24: lead wire -   25: IPM -   26: control circuit -   27: capacitor -   28: connector -   29: lid member -   30: high voltage circuit for motor drive -   31: shield plate -   37: noise filter -   41: motor wire wrap -   42: inverter -   43: power element -   44: motor control circuit -   45: low voltage circuit for control -   46: external power supply -   47: connector for high voltage -   48: air conditioning system -   49: connector for control signal -   58: case member -   59: component affixing hole -   60, 70, 80, 90: bus bar -   61, 71, 81, 91: small joining section 

1. An inverter-integrated electric compressor, wherein a motor is incorporated and a motor drive circuit including an inverter is provided in a housing space surrounded by a compressor housing, wherein a bus bar joint section at which bus bars are joined together to connect electrically is provided in said motor drive circuit, and that a tip, which is located at said bus bar joint section, of at least one of said bus bars is split into small joining sections.
 2. The inverter-integrated electric compressor according to claim 1, wherein said tips of both bus bars are provided with small joining sections.
 3. The inverter-integrated electric compressor according to claim 1, wherein at least one of said bus bars is provided as standing up from a board of said motor drive circuit.
 4. The inverter-integrated electric compressor according to claim 1, wherein at least one of said bus bars is provided on an IPM.
 5. The inverter-integrated electric compressor according to claim 1, wherein said joining is performed by a TIG welding.
 6. The inverter-integrated electric compressor according to claim 1, wherein the compressor is a compressor used for automotive air conditioning systems.
 7. The inverter-integrated electric compressor according to claim 6, wherein said compressor is mounted to an automotive engine. 